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#!/usr/bin/env python
# spdtool - Tool for partial deblobbing of UEFI firmware images
# Copyright (C) 2019 9elements Agency GmbH <patrick.rudolph@9elements.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
#
# Parse a blob and search for SPD files.
# First it is searched for a possible SPD header.
#
# For each candidate the function verify_match is invoked to check
# additional fields (known bits, reserved bits, CRC, ...)
#
# Dumps the found SPDs into the current folder.
#
# Implemented:
# DDR4 SPDs
#
import argparse
import crc16
import struct
class Parser(object):
def __init__(self, blob, verbose=False, ignorecrc=False):
self.blob = blob
self.ignorecrc = ignorecrc
self.verbose = verbose
@staticmethod
def get_matches():
"""Return the first byte to look for"""
raise Exception("Function not implemented")
def verify_match(self, header, offset):
"""Return true if it looks like a SPD"""
raise Exception("Function not implemented")
def get_len(self, header, offset):
"""Return the length of the SPD"""
raise Exception("Function not implemented")
def get_part_number(self, offset):
"""Return the part number in SPD"""
return ""
def get_manufacturer_id(self, offset):
"""Return the manufacturer ID in SPD"""
return 0xffff
def get_mtransfers(self, offset):
"""Return the number of MT/s"""
return 0
def get_manufacturer(self, offset):
"""Return manufacturer as string"""
id = self.get_manufacturer_id(offset)
if id == 0xffff:
return "Unknown"
ids = {
0x2c80: "Crucial/Micron",
0x4304: "Ramaxel",
0x4f01: "Transcend",
0x9801: "Kingston",
0x987f: "Hynix",
0x9e02: "Corsair",
0xb004: "OCZ",
0xad80: "Hynix/Hyundai",
0xb502: "SuperTalent",
0xcd04: "GSkill",
0xce80: "Samsung",
0xfe02: "Elpida",
0xff2c: "Micron",
}
if id in ids:
return ids[id]
return "Unknown"
def blob_as_ord(self, offset):
"""Helper for python2/python3 compatibility"""
return self.blob[offset] if type(self.blob[offset]) is int \
else ord(self.blob[offset])
def search(self, start):
"""Search for SPD at start. Returns -1 on error or offset
if found.
"""
for i in self.get_matches():
for offset in range(start, len(self.blob)):
if self.blob_as_ord(offset) == i and \
self.verify_match(i, offset):
return offset, self.get_len(i, offset)
return -1, 0
class SPD4Parser(Parser):
@staticmethod
def get_matches():
"""Return DDR4 possible header candidates"""
ret = []
for i in [1, 2, 3, 4]:
for j in [1, 2]:
ret.append(i + j * 16)
return ret
def verify_match(self, header, offset):
"""Verify DDR4 specific bit fields."""
# offset 0 is a candidate, no need to validate
if self.blob_as_ord(offset + 1) == 0xff:
return False
if self.blob_as_ord(offset + 2) != 0x0c:
return False
if self.blob_as_ord(offset + 5) & 0xc0 > 0:
return False
if self.blob_as_ord(offset + 6) & 0xc > 0:
return False
if self.blob_as_ord(offset + 7) & 0xc0 > 0:
return False
if self.blob_as_ord(offset + 8) != 0:
return False
if self.blob_as_ord(offset + 9) & 0xf > 0:
return False
if self.verbose:
print("%x: Looks like DDR4 SPD" % offset)
crc = crc16.crc16xmodem(self.blob[offset:offset + 0x7d + 1])
# Vendors ignore the endianness...
crc_spd1 = self.blob_as_ord(offset + 0x7f)
crc_spd1 |= (self.blob_as_ord(offset + 0x7e) << 8)
crc_spd2 = self.blob_as_ord(offset + 0x7e)
crc_spd2 |= (self.blob_as_ord(offset + 0x7f) << 8)
if crc != crc_spd1 and crc != crc_spd2:
if self.verbose:
print("%x: CRC16 doesn't match" % offset)
if not self.ignorecrc:
return False
return True
def get_len(self, header, offset):
"""Return the length of the SPD found."""
if (header >> 4) & 7 == 1:
return 256
if (header >> 4) & 7 == 2:
return 512
return 0
def get_part_number(self, offset):
"""Return part number as string"""
if offset + 0x15c >= len(self.blob):
return ""
tmp = self.blob[offset + 0x149:offset + 0x15c + 1]
return tmp.decode('utf-8').rstrip()
def get_manufacturer_id(self, offset):
"""Return manufacturer ID"""
if offset + 0x141 >= len(self.blob):
return 0xffff
tmp = self.blob[offset + 0x140:offset + 0x141 + 1]
return struct.unpack('H', tmp)[0]
def get_mtransfers(self, offset):
"""Return MT/s as specified by MTB and FTB"""
if offset + 0x7d >= len(self.blob):
return 0
if self.blob_as_ord(offset + 0x11) != 0:
return 0
mtb = 8.0
ftb = 1000.0
tmp = self.blob[offset + 0x12:offset + 0x12 + 1]
tckm = struct.unpack('B', tmp)[0]
tmp = self.blob[offset + 0x7d:offset + 0x7d + 1]
tckf = struct.unpack('b', tmp)[0]
return int(2000 / (tckm / mtb + tckf / ftb))
if __name__ == "__main__":
parser = argparse.ArgumentParser(description='SPD rom dumper')
parser.add_argument('--blob', required=True,
help='The ROM to search SPDs in.')
parser.add_argument('--spd4', action='store_true', default=False,
help='Search for DDR4 SPDs.')
parser.add_argument('--hex', action='store_true', default=False,
help='Store SPD in hex format otherwise binary.')
parser.add_argument('-v', '--verbose', help='increase output verbosity',
action='store_true')
parser.add_argument('--ignorecrc', help='Ignore CRC mismatch',
action='store_true', default=False)
args = parser.parse_args()
blob = open(args.blob, "rb").read()
if args.spd4:
p = SPD4Parser(blob, args.verbose, args.ignorecrc)
else:
raise Exception("Must specify one of the following arguments:\n--spd4")
offset = 0
cnt = 0
while True:
offset, length = p.search(offset)
if length == 0:
break
print("Found SPD at 0x%x" % offset)
print(" '%s', size %d, manufacturer %s (0x%04x) %d MT/s\n" %
(p.get_part_number(offset), length, p.get_manufacturer(offset),
p.get_manufacturer_id(offset), p.get_mtransfers(offset)))
filename = "spd-%d-%s-%s.bin" % (cnt, p.get_part_number(offset),
p.get_manufacturer(offset))
filename = filename.replace("/", "_")
filename = "".join([c for c in filename if c.isalpha() or c.isdigit()
or c == '-' or c == '.' or c == '_']).rstrip()
if not args.hex:
open(filename, "wb").write(blob[offset:offset + length])
else:
filename += ".hex"
with open(filename, "w") as fn:
j = 0
for i in blob[offset:offset + length]:
fn.write("%02X" % struct.unpack('B', i)[0])
fn.write(" " if j < 15 else "\n")
j = (j + 1) % 16
offset += 1
cnt += 1
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